1. Field of the Invention
The present invention relates to machines for grinding slots of ball cage members such as used in torque transmitting universal joints.
2. Description of the Prior Art
In grinding the slots of ball cage members, it is a basic requirement that, as shown in FIGS. 1 and 2, the edges in one side of the six slots Wp of a cage member W be ground into alignment with a line A and that edges Wb in the outer side of the six slots Wp be ground into alignment with another line B, thereby making the widths of the six cage slots Wp identical with one another in the axial direction of the cage member W.
However, a known grinding machine of this type as disclosed in U.S. Pat. No. 2,307,640 to A. H. Rzeppa is not designed to grind the edges Wa in one side of the six cage slots Wp with a common grinding wheel and to grind the edges Wa in the other side of the six cage slots Wp with another common grinding wheel. This causes the finish accuracy of the edges in either side to be degraded due to a variance in the infeed dead stop positions or in the dressing infeed end positions. Using the known grinding machine, it is therefore difficult and substantially impossible to grind the six cage slots Wp so that the six edges Wa in one side are aligned with the line A, and that the six edges Wb in the other side are aligned with the line B.